On Thu, Feb 22, 2024 at 09:48:09PM -0800, Selvarasu Ganesan wrote: > In scenarios of continuous and parallel usage of multiple FFS interfaces > and concurrent adb operations (e.g., adb root, adb reboot), there's a > chance that ffs_epfile_async_io_complete() might be processed after > ffs_epfile_release(). This could lead to a NULL pointer dereference of > ffs when accessing the ffs pointer in ffs_epfile_async_io_complete(), as > ffs is freed as part of ffs_epfile_release(). This epfile release is > part of file operation and is triggered when user space daemons restart > themselves or a reboot is initiated. > > Fix this issue by adding a NULL pointer check for ffs in > ffs_epfile_async_io_complete(). > > [ 9981.393115] Unable to handle kernel NULL pointer dereference at virtual address 00000000000001e0 > [ 9981.402854] Mem abort info: > ... > [ 9981.532540] Hardware name: Qualcomm Technologies, > [ 9981.540579] pstate: 204000c5 (nzCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > [ 9981.548438] pc : ffs_epfile_async_io_complete+0x38/0x4c > [ 9981.554529] lr : usb_gadget_giveback_request+0x30/0xd0 > ... > [ 9981.645057] Call trace: > [ 9981.648282] ffs_epfile_async_io_complete+0x38/0x4c > [ 9981.654004] usb_gadget_giveback_request+0x30/0xd0 > [ 9981.659637] dwc3_gadget_endpoint_trbs_complete+0x1a8/0x48c > [ 9981.666074] dwc3_process_event_entry+0x378/0x648 > [ 9981.671622] dwc3_process_event_buf+0x6c/0x288 > [ 9981.676903] dwc3_thread_interrupt+0x3c/0x68 > [ 9981.682003] irq_thread_fn+0x2c/0x8c > [ 9981.686388] irq_thread+0x198/0x2ac > [ 9981.690685] kthread+0x154/0x218 > [ 9981.694717] ret_from_fork+0x10/0x20 > > Signed-off-by: Selvarasu Ganesan <quic_selvaras@xxxxxxxxxxx> What commit id does this fix? Should it go to stable kernels? > --- > drivers/usb/gadget/function/f_fs.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c > index be3851cffb73..d8c8e88628f9 100644 > --- a/drivers/usb/gadget/function/f_fs.c > +++ b/drivers/usb/gadget/function/f_fs.c > @@ -849,7 +849,9 @@ static void ffs_epfile_async_io_complete(struct usb_ep *_ep, > usb_ep_free_request(_ep, req); > > INIT_WORK(&io_data->work, ffs_user_copy_worker); > - queue_work(ffs->io_completion_wq, &io_data->work); > + > + if (ffs && ffs->io_completion_wq) > + queue_work(ffs->io_completion_wq, &io_data->work); What happens if ffs->io_compleation_wq goes away right after you test it but before you call queue_work()? Where is the locking here to prevent that? thanks, greg k-h
